1. Field of the Invention
The present invention relates to split axle drive mechanisms, and more particularly to a split axle drive mechanism for part-time four-wheel drive vehicles which include a transfer device adapted to change the operating mode of the vehicle drive system between a two-wheel drive mode and a four-wheel drive mode.
2. Description of the Prior Art
In U.S. Pat. No. 4,625,584 granted to Onodera on Dec. 2, 1986, there has been proposed a split axle drive mechanism which comprises a first axle shaft connected to one side gear of a differential, a first output member arranged to be connected to the first axle shaft, a second axle shaft axially slidably connected to another side gear of the differential, a second output member arranged to be connected to the second axle shaft, a clutch mechanism disengageable for disconnecting the first axle shaft from the first output member when the vehicle is in a two-wheel drive mode and engageable for connecting the first axle shaft to the first output member when the vehicle is in a four-wheel drive mode, a connecting rod axially slidably disposed in the axle shafts and operatively connected at its one end with the clutch mechanism and at its other end with one end of the second axle shaft to be maintained in a first position for disconnecting the second axle shaft from the second output member in response to disengagement of the clutch mechanism and to be moved from the first position to a second position for connecting the second axle shaft to the second output member in response to engagement of the clutch mechanism, and a shift mechanism arranged to axially translate a clutch sleeve of the clutch mechanism between disengaged and engaged positions, the shift mechanism including a remotely controlled slide rod, and a lever arm connected at its one end with the slide rod and engaged at its other end with the clutch sleeve.
In the split axle drive mechanism, a coupling mechanism between the connecting rod and the second axle shaft and a coupling mchanism between the slide rod and the lever arm are arranged to connect the second axle shaft to the second output member after engagement of the clutch mechanism for effecting smooth meshing engagement between a spline wheel or the second axle shaft and an internally splined portion of the second output member. However, the coupling mechanisms are complicated in construction.